1. Field of the Invention
The present invention relates to a high-pressure heat exchanger including a plurality of tubes extending in parallel with one another, an inlet header pipe connected to one ends of the respective tubes and an outlet header pipe connected to the other ends of the respective tubes so that parallel flows of coolant are established between the both header pipes.
2. Prior Art
The well known parallel flow type heat exchanger of (such as a high-pressure condenser for a car air conditioner) usually comprises a plurality of flat tubes extending in parallel with one another, an inlet header pipe connected to one ends of the respective tubes and an outlet header pipe connected to the other ends of the respective tubes.
In such a heat exchanger of the prior art, connection of the each header pipe with the respective tubes has typically been achieved by (1) inserting each tube 23 into the corresponding one of insertion openings 22 formed through a wall of the header pipe 21 having circular cross-section, as illustrated by FIG. 7 (e.g., Japanese Patent Application Disclosure Gazette No. 1988-34466) or by (2) inserting each tube 28 into the corresponding one of insertion openings 27 formed through an end plate 26 which is, in turn, diametrically assembled with a tank 25 to form a header pipe 24, as illustrated by FIG. 8 (e.g., Japanese Patent Application Disclosure Gazette No. 1988-105400).
With such heat exchangers of the prior art, the desired heat exchange is achieved by parallel flows of coolant passing through said plurality of flat tubes extending between the inlet header pipe and the outlet header pipe.
However, in the arrangement set forth above in (1), it has been difficult to form the insertion openings for the flat tubes through the curved wall of the header pipe having a circular cross-section, and accordingly this has resulted in time-consuming work and increased cost for manufacturing.
In the arrangement set forth above in (2), on the other hand, formation of the insertion openings through the end plate has certainly been facilitated by the two-component structure of the header pipe, but this arrangement has still been inconvenient because the pressure resistance of the end plate to the coolant flowing through the header pipe along a junction between the end plate and the tank is lowered, and because the end plate is substantially planar and is tightly joined to the tank on the outer surface thereof.
The present invention has been made to provide, in view of the above-mentioned problems encountered by the heat exchanger of the prior art, an effective solution to such problems.